New manpage.

doc/crypto/BN_mod_mul_montgomery.pod

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+=pod
+
+=head1 NAME
+
+BN_mod_mul_montgomery, BN_MONT_CTX_new, BN_MONT_CTX_init,
+BN_MONT_CTX_free, BN_MONT_CTX_set, BN_MONT_CTX_copy,
+BN_from_montgomery, BN_to_montgomery - Montgomery multiplication
+
+=head1 SYNOPSIS
+
+ #include <openssl/bn.h>
+
+ BN_MONT_CTX *BN_MONT_CTX_new(void);
+ void BN_MONT_CTX_init(BN_MONT_CTX *ctx);
+ void BN_MONT_CTX_free(BN_MONT_CTX *mont);
+
+ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *m, BN_CTX *ctx);
+ BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from);
+
+ int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
+         BN_MONT_CTX *mont, BN_CTX *ctx);
+
+ int BN_from_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
+         BN_CTX *ctx);
+
+ int BN_to_montgomery(BIGNUM *r, BIGNUM *a, BN_MONT_CTX *mont,
+         BN_CTX *ctx);
+
+=head1 DESCRIPTION
+
+These functions implement Montgomery multiplication. They are used
+automatically when BN_mod_exp(3) is called with suitable input,
+but they may be useful when several operations are to be perfomed
+using the same modulus.
+
+BN_MONT_CTX_new() allocates and initializes a B<BN_MONT_CTX> structure.
+BN_MONT_CTX_init() initializes an existing uninitialized B<BN_MONT_CTX>.
+
+BN_MONT_CTX_set() sets up the B<mont> structure from the modulus B<m>
+by precomputing its inverse and a value R.
+
+BN_MONT_CTX_copy() copies the B<N_MONT_CTX> B<from> to B<to>.
+
+BN_MONT_CTX_free() frees the components of the B<BN_MONT_CTX>, and, if
+it was created by BN_MONT_CTX_new(), also the structure itself.
+
+BN_mod_mul_mont() computes Mont(B<a>,B<b>):=B<a>*B<b>*R^-1 and places
+the result in B<r>.
+
+BN_from_montgomery() performs the Montgomery reduction B<r> = B<a>*R^-1.
+
+BN_to_montgomery() computes Mont(B<a>,R^2).
+
+For all functions, B<ctx> is a previously allocated B<BN_CTX> used for
+temporary variables.
+
+The B<BN_MONT_CTX> structure is defined as follows:
+
+ typedef struct bn_mont_ctx_st
+        {
+        int use_word;   /* 0 for word form, 1 for bignum form */
+        int ri;         /* number of bits in R */
+        BIGNUM RR;      /* R^2 (used to convert to Montgomery form) */
+        BIGNUM N;       /* The modulus */
+        BIGNUM Ni;      /* The inverse of N (bignum form) */
+        BN_ULONG n0;    /* The inverse of N in word form */
+        int flags;
+        } BN_MONT_CTX;
+
+BN_to_montgomery() is a macro.
+
+=head1 RETURN VALUES
+
+BN_MONT_CTX_new() returns the newly allocated B<BN_MONT_CTX>, and NULL
+on error.
+
+BN_MONT_CTX_init() and BN_MONT_CTX_free() have no return values.
+
+For the other functions, 1 is returned for success, 0 on error.
+The error codes can be obtained by ERR_get_error(3).
+
+=head1 SEE ALSO
+
+bn(3), err(3), BN_add(3), BN_CTX_new(3)
+
+=head1 HISTORY
+
+BN_MONT_CTX_new(), BN_MONT_CTX_free(), BN_MONT_CTX_set(),
+BN_mod_mul_montgomery(), BN_from_montgomery() and BN_to_montgomery()
+are available in all versions of SSLeay and OpenSSL.
+
+BN_MONT_CTX_init() and BN_MONT_CTX_copy() were added in SSLeay 0.9.1b.
+
+=cut